As every lawyer knows, the prosecutor is the most powerful figure in the American criminal justice system. The prosecutor decides whom to charge, what charges to bring, whether to permit a defendant to plead guilty, and whether to confer immunity. In carrying out this broad decision-making power, the prosecutor enjoys considerable independence. Indeed, one of the most elusive and vexing subjects in criminal justice has been to define the limits of the prosecutor’s discretion.
Bennett L. Gershman, The Most Fundamental Change in the Criminal Justice System: The Role of the Prosecutor in Sentence Reduction, Crim. Just., Fall 1990 at 2, http://digitalcommons.pace.edu/lawfaculty/412/.